[Robyo]

Is it called “Ducking?”   Reason used this term for a type of side chain comp.

from wikipedia:
Ducking is an effect commonly used in radio and pop music, especially dance music. It is an effect where the level of one signal is reduced by the presence of another signal, through the use of side chain compression. A typical application is to automatically lower the level of a musical bed when a voice-over starts, and to automatically bring the level up again when the voice-over stops. It can also be used to achieve a “pumping” effect which can clearly be heard in “Call On Me” by Eric Prydz, and “Hung Up” by Madonna.